WetBulb Globe Temperature

Heat, Severe and Fire Weather

Excessive heat warnings persist across the Desert Southwest, while the heat and humidity lingers along the East Coast. An extensive zone of strong to severe thunderstorms with damaging winds and locally heavy rain are expected along a strong cold front from New England to the south-central Plains. Finally, elevated fire weather threats/red flag warnings are likely across the Inter-mountain West. Read More >

WetBulb Globe Temperature (Prototype-Under Development. Not to be used for operational use)

The WetBulb Globe Temperature (WBGT) is a measure of the heat stress in direct sunlight, which takes into account: temperature, humidity, wind speed, sun angle and cloud cover (solar radiation). This differs from the heat index, which takes into consideration temperature and humidity and is calculated for shady areas. If you work or exercise in direct sunlight, this is a good element to monitor. Military agencies, OSHA and many nations use the WBGT as a guide to managing workload in direct sunlight.

Initial values are estimates for the selected location adjust sliders as needed
Month:
Day:
Latitude:
Fcst Max Temp(F):	80
DewPoint(F):	70
RH(%):
Wind Speed(mph):
Cloud Cover(%):

HeatIndex(F):	88
WBGT(F):	88

WetBulb Globe Temperature

Heat Index

Comparison with Heat Index

	WBGT	Heat Index
Measured in the sun
Measured in the shade
Uses Temperature
Uses RH
Uses Wind
Uses Cloud Cover
Uses Sun Angle

Examples

Temp F	Dwpt F	RH %	Sky %	Wind mph	HeatIdx F	WBGT F
90	65	42	05	03	92	89
90	65	42	05	13	92	83
90	65	42	65	13	92	81
90	70	52	10	06	96	88
90	70	52	60	06	96	86
90	70	52	60	13	96	85
100	70	39	10	13	108	90
100	70	39	10	5	108	94
100	70	39	65	05	108	91

Preparedness - What to do before doing outdoor activities when the WBGT is high -

Wear a hat and light weight, light fitting, light colored clothes.
Plan to take frequent breaks in shady areas.

Safety - What to do while doing outdoor activities when the WBGT is high -
Take breaks in the shade. Strenuous outdoor activities should be reduced, especially in direct sunlight where there is little ventilation.
Drink plenty of water or other non-alcohol fluids. Your body needs water to keep cool. Drink plenty of fluids even if you don’t feel thirsty.
Don’t get too much sun. Sunburn makes the job of heat dissipation that much more difficult

Suggested Actions and Impact Prevention

WBGT(F)

Effects

Precautionary Actions

< 80

80-85

Working or exercising in direct sunlight will stress your body after 45 minutes.

Take at least 15 minutes of breaks each hour if working or exercising in direct sunlight

85-88

Working or exercising in direct sunlight will stress your body after 30 minutes.

Take at least 30 minutes of breaks each hour if working or exercising in direct sunlight

88-90

Working or exercising in direct sunlight will stress your body after 20 minutes.

Take at least 40 minutes of breaks each hour if working or exercising in direct sunlight

>90

Working or exercising in direct sunlight will stress your body after 15 minutes.

Take at least 45 minutes of breaks each hour if working or exercising in direct sunlight